Current Organic Chemistry - Volume 8, Issue 1, 2004

In this issue of Current Organic Chemistry several analytical methods to solve problems associated with the keto-enoltautomerism, molecular recognition and the stereochemistry of small and macromolecules are covered. E. Iglesias reviews work done on keto-enol / enolate equilibria in constrained media, such as aqueous solutions of surfactants forming micelles or cyclodextrins. The discussion offers new insights into en Read More

Keto-enol tautomerism has been the subject of continuous interest in chemistry. Enols and enolate ions are essential intermediates in many important chemical reactions, and a number of biological transformations also involve enol formation. Enolization, moreover, has long been of interest as an example of tautomeric rearrangement. One of the things that one would like to know about enols is the magnitude of keto Read More

The length of guest molecules determines the stoichiometry of inclusion complexes of long endfunctionalized molecules with cyclodextrins in aqueous solution. Molecules up to 10-12 Å form primarily 1:1 host:guest adducts, even if they have to curve inside the cavity, whereas longer molecules form mixtures of 1:1 and 2:1 adducts in equilibrium with each other. The width of the cyclodextrin cavity determines the host- Read More

This review describes the spectroscopic studies on molecular recognition of a wide variety of guest molecules with native and modified cyclodextrins, including monomodified cyclodextrins, and functional group-bridged bis(cyclodextrin)s. Steady-state and time-resolved fluorescence spectroscopy, circular dichroism spectroscopy, UV-vis spectroscopy, and two-dimensional NMR spectroscopy can be taken to determine Read More

Biosynthetic incorporation of selenium- and tellurium- containing amino acids has been exploited to produce both heavy-atom derivatives and nuclear magnetic resonance probes in biomacromolecules. These derivatives have played a significant role in the elucidation of both the local and global structures of a variety of biomacromolecules such as proteins and oligomeric nucleic acids. Although the replacement of methion Read More

Circular dichroism spectroscopy based on exciton coupling (ECCD) is a powerful tool for stereochemical analysis of organic compounds, i.e. for the determination of absolute configuration as well as conformation. Although the method is widely used for more than three decades, only in the past decade advances have been made toward making the ECCD method more sensitive and user-friendly. The newly developed extended π- Read More